For the mother clucker: Combine fish sauce, lime juice, garlic and 1 cup sugar in a mixing bowl. Whisk well and pour over chicken in a bowl. Let marinate, covered and refrigerated, overnight.
Shred carrots and daikon and mix in a bowl, then set aside. Add rice vinegar, chile flakes, remaining cup sugar and 1 cup water to a medium saucepan. Turn heat on medium and cook, stirring constantly, until sugar has completely dissolved. Let cool to room temperature, then pour over carrots and daikon. Refrigerate until ready to serve.
Preheat a grill for cooking at about 400 degrees F.
Remove chicken from marinade and discard marinade. Grill chicken until it reaches an internal temperature of 165 degrees F. Dice chicken.
For the bun daddy bun: Meanwhile, combine water, sugar and yeast in a stand mixer. Stir well and wait for foam to form, about 5 minutes.
Mix flour and baking powder together in a separate bowl and stir until mixed well.
Add 6 tablespoons oil to the yeast mixture, then add and combine the dry ingredients. Turn the mixer on low speed to incorporate everything, then mix on medium speed until a smooth dough ball has formed, 10 to 15 minutes. Remove dough from mixing bowl and oil the sides of the bowl. Place the dough back in the bowl, cover with plastic wrap and set in warm place to proof until dough has doubled in size, 1 to 2 hours.
Knead dough for 2 to 3 minutes, removing any air bubbles. Portion dough out to
roughly 2-ounce balls. Let dough proof again, loosely covered, for about 10 minutes.
Flatten dough balls with your palm and roll out to 1/4-inch-thick discs. Drop 1 to 2 drops of oil on the inside of a dough disc, fold in half and place in a bamboo steamer. Repeat with the remaining dough.
Steam buns for 12 minutes. Remove from heat, then top with chicken, mayo, hoisin, cucumber, jalapeno, daikon/carrot pickles and radish greens. (Save remaining buns for another use.)
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.